i965/fs: Fix broken math on values loaded from uniform buffers on gen6.
i965/fs: Fix broken math on values loaded from uniform buffers on gen6.

In a debug build this led to assertion failures, but on a non-debug
build the hardware would just reference the whole vec8 instead of the
same channel 8 times.

Fixes the new piglit glsl-1.40/uniform-buffer/fs-exp2.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=57121
Note: This is a candidate for the stable branches
Reviewed-by: Kenneth Graunke <bd2562f754ec92342f93f61c25d731e290a2ffa8@whitecape.org>

metora/MesaGLSLCompiler,jbarczak/glsl-optimizer,mapbox/glsl-optimizer,zeux/glsl-optimizer,wolf96/glsl-optimizer,jbarczak/glsl-optimizer,benaadams/glsl-optimizer,zeux/glsl-optimizer,benaadams/glsl-optimizer,bkaradzic/glsl-optimizer,metora/MesaGLSLCompiler,jbarczak/glsl-optimizer,mapbox/glsl-optimizer,benaadams/glsl-optimizer,djreep81/glsl-optimizer,bkaradzic/glsl-optimizer,mapbox/glsl-optimizer,zz85/glsl-optimizer,dellis1972/glsl-optimizer,tokyovigilante/glsl-optimizer,mapbox/glsl-optimizer,mcanthony/glsl-optimizer,mcanthony/glsl-optimizer,dellis1972/glsl-optimizer,zz85/glsl-optimizer,wolf96/glsl-optimizer,djreep81/glsl-optimizer,zeux/glsl-optimizer,metora/MesaGLSLCompiler,wolf96/glsl-optimizer,mcanthony/glsl-optimizer,zeux/glsl-optimizer,wolf96/glsl-optimizer,dellis1972/glsl-optimizer,benaadams/glsl-optimizer,benaadams/glsl-optimizer,zz85/glsl-optimizer,djreep81/glsl-optimizer,benaadams/glsl-optimizer,bkaradzic/glsl-optimizer,jbarczak/glsl-optimizer,tokyovigilante/glsl-optimizer,mcanthony/glsl-optimizer,bkaradzic/glsl-optimizer,tokyovigilante/glsl-optimizer,mapbox/glsl-optimizer,djreep81/glsl-optimizer,djreep81/glsl-optimizer,bkaradzic/glsl-optimizer,zeux/glsl-optimizer,tokyovigilante/glsl-optimizer,zz85/glsl-optimizer,dellis1972/glsl-optimizer,zz85/glsl-optimizer,dellis1972/glsl-optimizer,mcanthony/glsl-optimizer,zz85/glsl-optimizer,wolf96/glsl-optimizer,tokyovigilante/glsl-optimizer,jbarczak/glsl-optimizer